Developing Data Structures
Create iterators that cycle over the city information map associated with the new city.
travelCosts[newCity] = cost;
cityInfo::iterator start = cityMap[newCity].begin();
cityInfo::iterator stop = cityMap[newCity].end();
for (; start != stop; ++start) {const char * destCity = (*start).first;// make the new routineunsigned int destDistance = (*start).second;que.push(Destination(destCity, cost + destDistance));